Pegula had already secured her spot in Saturday’s semi-finals by beating both Sabalenka and Rybakina in her earlier matches in Mexico.
But the American is yet to drop a set so far this tournament and it took her just under 80 minutes to beat Sakkari, who failed to qualify for the semi-finals after losing all of her games.
Sabalenka won the first set 6-2 in the Australian Open final rematch on a rain interrupted evening and had Rybakina on the ropes early in the second set.
But Rybakina fought back to take the lead 5-3 before the match was called off for the night, with play to resume on Friday.
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